While other "over-the-top" providers have existed for years, this decision was pivotal because it was the first time that any major content provider decided to break with the traditional cable delivery model and go direct to consumer.  Within a year, HBO Now had amassed 1 million subscribers.  Meanwhile, Pay TV households collapsed around the same time as "cord cutting" accelerated.

Per the following data from Barclays' Media and Telecom analyst, Kannan Venkateshwar, the decline of Pay TV households really accelerated in 2Q 15 around the same time that HBO Now was launched.